1. Field of the Invention
The present invention relates generally to a wireless communication system, and in particular, to a wireless communication base station sharing apparatus for sharing an antenna and a feeder cable in deploying wireless communication systems that provide services in different frequency bands.
2. Description of the Related Art
As illustrated in FIGS. 1A, 1B and 1C, a plurality of service providers provide services through independent base stations (BSs) 10 and 12 in cellular, CDMA, PCS and GSM mobile communication systems and other wireless communication systems. The resulting redundant investment regarding installation of individual BSs and unnecessary existence of too many BSs in an adjacent area lead to signal quality degradation due to mutual interference between the BSs.
As it has occurred recently that one service provider merges other service providers and thus needs to provide services, integrating the frequency bands of the service providers. In this case, a need exists for unifying the existing system with the added systems to reduce cost. One service provider may be assigned different frequencies in different areas in overseas. He must deploy BS systems operating in different frequency bands locally.
To overcome this problem, techniques for sharing a BS have been developed. One of the techniques is to share a BS antenna and a feeder cable by use of a new quadroplexer 132 covering the frequency bands of an existing BS system, for example, a system 10 (system A) and a sub-BS system, for example, a system 12 (system B), as illustrated in FIG. 1C.
This technique requires fabrication of such a quadroplexer as allows two systems to share an antenna and a feeder cable. Moreover, in case of different frequency bands assigned to a service provider in different areas, many quadroplexers must be fabricated. If the frequency band of a subsystem is changed while the subsystem is operated, sharing an antenna and a feeder cable with a main system, a new quadroplexer is needed. If a plurality of subsystems are added, a plurality of new quadroplexers are to be fabricated.
As described above, since a new quadroplexer must be fabricated to share an antenna and a feeder cable between an existing main system and an added subsystem in the conventional technology. Therefore, fabrication cost and management cost are increased.